How is food digested and absorbed?

Digestion is the process by which food is broken down into small molecules in the digestive tract, and the process by which digested nutrients enter the blood or lymph fluid through the mucous membrane of the digestive tract is called absorption. The digestive functions and characteristics of each digestive tract are as follows

1) Oral digestion: The salivary glands in the oral cavity secrete saliva, which can moisten and dissolve food, making it easy to swallow; Saliva contains salivary amylase, lysozyme, and immunoglobulins. Salivary amylase hydrolyzes starch into maltose, and lysozyme and immunoglobulins have bactericidal and virucidal effects that protect and clean the oral cavity.

2) Gastric digestion: including mechanical digestion and chemical digestion. Chemical digestion, which breaks down and digests food through the action of gastric juice.

Hydrochloric acid (gastric acid): activates pepsinogen and favors protein hydrolysis; Kills bacteria that enter the stomach with food; The acidic environment created by hydrochloric acid favors the absorption of iron and calcium in the small intestine. Mucus:

Protects the gastric mucosa from damage by hydrochloric acid and pepsin in the stomach, lubricates food. Intrinsic factor: secreted by parietal cells.

Prevents the destruction of vitamin B12 by intestinal hydrolytic enzymes and promotes its absorption. Mechanical digestion is the peristalsis of the stomach that grinds the food, mixes it well with the digestive juices, pushes it to the distal end of the digestive tract, and empties the stomach to allow the food to enter the duodenum.

3) Digestion in the small intestine: The small intestine is the most important part of food digestion and absorption. The pancreatic juice in the small intestine can hydrolyze proteins, starches, and fats; The small intestine is conducive to the chemical digestion of chyme through segmental movement, and promotes the return of blood and lymph to facilitate absorption.

4) Digestion in the large intestine: The large intestine has no important digestive activity. It mainly absorbs water and inorganic salts, but also provides a temporary storage place for food residues after digestion and absorption, and converts food residues into feces.

This requires the participation of people as a whole.

How is food digested? You'll know after watching this animation!

Food into the stomach, it takes four hours to be decomposed and digested by the stomach, and then the stomach transports food to the small intestine, after further decomposition and absorption, the components needed by the body are absorbed, and the unwanted ones will be sent to the large intestine, which has to be discharged from the body through intestinal peristalsis, each person's physique is different, and the time of discharge is also different, basically it takes about 8 to 10 hours, usually take more dietary fiber food, which helps to discharge toxins and exhaust gases from the body The digestion of food begins from the mouth, Food is mainly mechanically digested in the mouth (food is ground) because the food stays in the mouth for a short time, so the digestion in the mouth is not very effective. After the food enters the stomach from the esophagus, it is subjected to the mechanical digestion of the gastric wall muscles and the chemical digestion of gastric juice, at this time, the protein in the food is initially decomposed by pepsin in the gastric juice (with the participation of gastric acid), and the gastric contents become a porridge-like chyme state, which is pushed to the duodenum through the pylorus many times in small quantities. After the chyme enters the duodenum from the stomach, it begins digestion in the small intestine.

The small intestine is the main site of digestion and absorption. Food is chemically digested in the small intestine by pancreatic juice, bile and intestinal fluid, as well as mechanical digestion by the small intestine, and various nutrients are gradually broken down into simple absorbable small molecules that are absorbed in the small intestine. As a result, after food passes through the small intestine, the digestion process is almost complete, leaving only the indigestible food residues, which enter the large intestine from the small intestine.

There is no digestion in the large intestine, and it only has a certain absorption function.

What is the digestion process like? It first passes through the mouth, then through the stomach, and finally through the large intestine and small intestine, and finally it is excreted as food residue.

Absorption of food.

Absorption is the process by which food is digested and becomes small molecules that pass through the mucous membranes of the digestive tract into the bloodstream and lymph. Vanish.

Chemistry and absorption are two complementary and closely related processes. Digestion is an important prerequisite for absorption, and absorption is the body's response.

An important guarantee for the utilization of nutrients. The ability and rate of absorption in different parts of the digestive tract depends on the parts of the digestive tract.

Tissue structure, as well as the extent to which food is digested in various parts and how long it stays. In the mouth and esophagus, food is almost none.

is absorbed; The stomach absorbs only a small amount of water and alcohol; Only the small intestine is the main site of absorption; Three major nutrients.

Most of the digestive products are absorbed in the duodenum and jejunum, and the ileum actively absorbs bile salts and vitamin B12. For large.

Some of the nutrients are usually absorbed by the time they reach the ileum, so when the contents of the small intestine enter the large intestine, they contain a very small amount of material that can be absorbed. The large intestine mainly absorbs water and salts.

Once nutrients have been digested and absorbed, they must be transported to tissues where they are needed or stored. Blood and lymph are the main carriers of absorbed nutrients. Most of the nutrients are absorbed into the blood circulation and then with the blood.

Protein molecules bind and are transported to various tissues and cells. Lipid digestion products are treated by the intestinal mucosa in the lymphatic capillary network-like group.

After tissue absorption, it enters the lymphatic fluid, which is transported through the lymphatic system and then enters the blood circulation.

Proteins and carbohydrates are broken down into amino acids and monosaccharides, respectively, in the mucosa of the small intestine in the digestive tract to take an active role.

It is absorbed by transport and enters the blood circulation for the body to use. Fats are digested into glycerol and fatty acids, which can be absorbed directly into the bloodstream, while most of the fatty acids enter the capillary lymphatic vessels and enter the blood circulation through the large lymphatic vessels. Fat-soluble vitamins are absorbed along with fatty acids.

Small nutrients present in food, such as water, vitamins and minerals, are directly absorbed in the small intestine. Water absorption is done by osmotic pressure, and water-soluble vitamins are diffusion.

Different minerals are absorbed in different ways.

It should be pointed out that there is an essential difference between dyspepsia and malabsorption. When there is a problem with the pancreas and liver, the secretion of digestive enzymes and digestive juices in the small intestine is affected, and indigestion symptoms will occur. And malabsorption is often caused by the intestines.

Caused by rapid peristalsis or abnormal function of the small intestine. Because indigestion and malabsorption occur in the small intestine, it is sometimes difficult to distinguish the two completely.

Do you want to know if the nutrients you eat are absorbed?

In fact, foods with high calcium content abound around us. Milk contains 100 120 mg of calcium per 100 grams of natural food, and about 240 280 mg of calcium per bag of commercially available milk, and is easily absorbed by the human body, making it the most ideal source of calcium. If a child drinks 250 milliliters of milk and a cup of yogurt a day, he can supplement 400 500 milligrams of calcium, supplemented with calcium-rich vegetables, soy products, etc., which can basically meet the calcium needs.

Beans, fish and shrimp, dried fruits such as hazelnuts and peanuts, kelp, fungus, shiitake mushrooms, sesame sauce and many green vegetables are good for calcium**. Tofu adds some electrolytes in the process of marinating to precipitate the protein, such as gypsum in southern tofu, that is, calcium sulfate, and northern tofu in brine, which is magnesium-containing salt, which is also beneficial to calcium supplementation.

In the daily cooking process, attention should also be paid to reducing the loss of calcium. If food should be stored safely; Do not stir when heating the milk to avoid the loss of calcium; Vegetables should be washed before cutting, should not be cut too much, stir-fry should add more water, cooking time should not be too long; Vegetables containing more oxalic acid, such as spinach, should be blanched with hot water to dissolve oxalic acid.